* Similar to links add the ability to add prefixes in a generic way. We have the following needs:
* image where the source is at a URL
* image where the source is at a relative path
* image where the source is in a document
I propose the following syntax:
where prefix = one of http:, path:, attach:
Note that we already support image:http://... so the proposal here is simply to make it generic.
In addition I propose that when there's no prefix or if the prefix is unknown then to consider that the image is to be found in a document (equivalent to attach:).
Same pros as above.